SAN DIEGO (AP) -- Bennie Boatwright hobbled out of Jenny Craig Pavilion on crutches and his sprained left knee in a brace, an injury that put a damper on Southern California's 76-55 victory against San Diego and left the undefeated Trojans wondering how long they'll be without their second-leading scorer.

The 6-foot-10 sophomore forward was hurt when he collided with USD's Juwan Gray while taking a shot just three minutes in. Boatwright stayed on the floor for a few minutes while being tended to and had to be helped to the bench. He also had to be helped into the locker room at halftime.

Coach Andy Enfield said Boatwright will have an MRI exam on Thursday.

"We're hoping it's just a sprain," Enfield said. "We're hoping for the best. He'll certainly be out for a while. We're hoping it's a few weeks vs. the season."

Chimezie Metu had 19 points and 13 rebounds, and Elijah Stewart scored 15 points for the Trojans (7-0), who led the whole way in beating the Toreros for the second straight season. De'Anthony Melton added 14.

Boatwright, who missed the first two games with back spasms, was averaging 13.5 points.

"It has an effect because our rotation is not the same as it would be with him in there. He's a unique player, with his size and his guard skills," Enfield added. "We had to go small, and then we went big. Thank goodness Chimezie is skilled enough to play both front-line positions. ... Our players just have to step up."

Metu agreed.

"It's one less scoring option on offense. At times when we didn't have him it was hard for us to score. We're just going to have to work through it."

USC was too big and talented for the Toreros, particularly the 6-foot-11 Metu, who was 9 of 11 from the floor. He dominated on the boards and scored eight of the Trojans' final 12 points of the first half en route to a 43-31 lead. He had a tip-in off a rebound, a turnaround jumper, a jump hook and a slam dunk off a rebound.

The teams combined to miss 14 straight shots early in the second half, each going about six minutes without scoring.

Metu broke the Trojans' drought with a slam dunk on an alley-oop pass from Jordan McLaughlin.

BIG PICTURE

USC: The Trojans are off to their best start since going 8-0 to open the 2000-01 season. They finished 24-10 after reaching the Elite Eight.

USD: The Toreros dropped to 0-6 all-time against the Trojans. The Toreros opened last season at USC, losing 83-45.

"We've just got to continue to chop wood," San Diego coach Lamont Smith said. "We've got to have our freshmen grow up. Right now they haven't played at a high enough clip, and with half our team being freshmen, they've got to produce."

UP NEXT

USC plays BYU in the Hoophall LA game at Staples Center on Saturday. The game is part of a doubleheader, with No. 8 Gonzaga and 16th-ranked Arizona playing the first game. USC is 6-3 all-time against BYU.